Non-Linear Relationships Between Creativity Ratings of Musical Improvisations and Melodic Complexity

Although objective, automated measures of verbal creativity have shown promise by correlating well with subjective creativity ratings, objective measures of musical creativity remain underexplored. This study investigated whether melodic complexity – specifically the Lempel-Ziv complexity of pitch sequences – is related to perceived musical creativity in improvisations. We further investigated whether this relationship is affected by participants’ openness to experience and musical expertise. In an online study, 495 participants with at least five years of musical experience rated improvisations on liking, originality, and appropriateness. They also completed the openness to experience scale of the Big Five Inventory and provided information about their musical expertise. Results revealed inverted U-shaped relationships between Lempel-Ziv complexity and ratings, with improvisations of moderate complexity receiving the highest evaluations. However, openness to experience did not significantly affect this relationship. Participants with greater musical expertise tended to rate improvisations lower overall, while they rated improvisations made by professionals higher than those by amateurs on liking and appropriateness, highlighting the role of expertise in evaluation. These findings demonstrate individual differences in the assessment of musical creativity. While Lempel-Ziv complexity is a relatively simple metric, the results suggest its potential for informing the development of quantitative measures of musical creativity.